static int num = 0; //当加载模块不指定num的值时则为0

#define module_param(name, type, perm) \

module_param_named(name, name, type, perm)
#define module_param_named(name, value, type, perm)  \

param_check_##type(name, &(value));  \

module_param_call(name, param_set_##type, param_get_##type, &value, perm); \

__MODULE_PARM_TYPE(name, #type)
#define module_param_call(name, set, get, arg, perm)   \

__module_param_call(MODULE_PARAM_PREFIX,   \

  name, set, get, arg,   \

  __same_type(*(arg), bool), perm)
#define __module_param_call(prefix, name, set, get, arg, isbool, perm) \

static int __param_perm_check_##name __attribute__((unused)) = \

BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)) \

+ BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN); \

static const char __param_str_##name[] = prefix #name; \

static struct kernel_param __moduleparam_const __param_##name \

__used \

  __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \

= { __param_str_##name, perm, isbool ? KPARAM_ISBOOL : 0, \

  set, get, { arg } }

test-objs := a.o b.o //由a.c, b.c 编成test.ko, 注意不能有.o文件与目标ko文件同名
obj-m += test.o

EXPORT_SYMBOL_GPL(函数名)
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